Puzzled -40-180 - Printable Version
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Puzzled -40-180 - Patrick - 04-18-2020
What's happening here? The 6 meg tone control (51) is switched. That's why the dotted line. But the wiper can't be grounded, or the .01 cap, 40a, would just be shorted to ground. Why does the wiper have a circle for connection, instead of a dot? It appears the actual pot has nothing connector to the wiper. How does this tone control work?
I'm confused.
[Image: https://i.imgur.com/e9jYt0n.jpg]
RE: Puzzled -40-180 - morzh - 04-18-2020
It is correct.
The wiper simply brings GND closer to the C50, cutting out the treble, or further away, letting the treble through.
RE: Puzzled -40-180 - Patrick - 04-18-2020
Got it. I'm getting old. I guess.
RE: Puzzled -40-180 - rfeenstra - 04-18-2020
Well I have a question too! where does the phase inversion come from for the push pull? Does it come from the screen grid of the upper 41, through the .01 cap #52?
RE: Puzzled -40-180 - Radioroslyn - 04-18-2020
Yup...
RE: Puzzled -40-180 - morzh - 04-18-2020
This is called "Paraphase inverter".
It is described here.
https://dalmura.com.au/static/Phase%20Inversion%20Circuits%20Radio%20Craft%201948.pdf
Look at Fig. 10.
RE: Puzzled -40-180 - rfeenstra - 04-19-2020
Thanks guys! I like the line "results are disappointing..." I would think there would be some phase problems between the 2 output tubes, but I've never played with the circuit.